The invention relates to a guide arrangement for linear sliding movements of guide shoes along guide rails for sliding roofs.
For the purposes of this description, the term “sliding roofs” includes all designs in which at least one cover is associated in displaceable fashion with a roof opening of a motor vehicle and in this respect can slide by means of guide shoes along guide rails which are applied laterally along the roof opening. These include not just designs in which the cover can be slid under the rear fixed roof surface after lowering its rear edge in order to free the roof opening, but also so-called sliding-lifting roofs where the cover can additionally be pivoted from its position which closes the roof opening about a pivot axis provided in the vicinity of its front edge in order to be extended beyond the fixed roof surface. Finally, this definition is also intended to comprise designs in which, after lifting its rear edge, the cover can be displaced more or less to the rear beyond the rear fixed roof surface (so-called overhead sliding roofs, spoiler roofs). Also to be included are roof designs in which the cover, of which there is at least one, is not formed from sheet metal or glass, but instead as a collapsible roof of a flexible flat material.
Two front and two rear guide shoes are as a rule provided for sliding covers of sliding roofs, which shoes are in each case disposed in pairs. The front guide shoes guide the front end, mounted by means of a pivot bearing, of the cover. The elements for vertically displacing the cover and the drive elements effecting the sliding drive (e.g., flexible drive cables guided in bending-resistant fashion, with a threaded winding for the engagement of a drive pinion) are connected to the rear guide shoes.
The slide elements at the guide shoes are formed according to the prior art either as slide pieces which are guided in U-shaped guide grooves, which form the slideways (e.g., DE 197 27 738 C1), or as U-shaped sliders which are guided at guide webs, which form the slideways, of the guide rails. In both cases the slide pieces or sliders are disposed in opposite pairs at the guide shoes, have large-area slide pair surfaces and as a rule lie in one plane.
The slide elements should be guided in sliding fashion at the guide rails without rattling, yet with the lowest possible friction level. However, interference or loose fits occur in this case due to manufacturing tolerances. Interference fits result in high coefficients of friction and a high level of wear, while loose fits are seldom rattle-free. Even slight soiling of the slideways at the guide rails may increase these undesirable effects further.